An efficient numerical approach, for determining the dispersion characteristics of dual-mode elliptical-core optical fibers

Based on vectorial formulations which combine the surface integral equation method and the finite-element method, a novel numerical approach is proposed for calculating the dispersion coefficients of dual-mode elliptical-core fibers with arbitrary refractive index profiles. By differentiating the original formulations involving the propagation constant /spl beta/ and the guided mode fields H/sub x/ and H/sub y/ once and twice with respect to the normalized frequency V, the new formulations for {d/spl beta//dV, dH/sub x//dV, dH/sub y//dV} and for {d/sup 2//spl beta//dV/sup 2/, d/sup 2/H/sub x//dV/sup 2/, d/sup 2/H/sub y//dV/sup 2/} are obtained respectively. Once {/spl beta/, H/sub x/, H/sub y/} is solved through the eigenvalue procedure which dominates the computing time, only a few matrix manipulations are required to obtain {d/spl beta//dV, dH/sub x//dV, dH/sub y//dV} and {d/sup 2//spl beta//dV/sup 2/, d/sup 2/H/sub x//dV/sup 2/, d/sup 2/H/sub y//dV/sup 2/}. Some numerical examples are examined to see the influence of different refractive index distributions with dips on the dispersions of the four nondegenerate LP/sub 11/ modes for elliptical-core fibers.<
>